Q. A 35-year-old man presents to his primary care physician with a three-month history of easy bruising and frequent nosebleeds. He reports that these episodes have been progressively worsening and that he has been feeling more tired than usual. He has a family history of similar symptoms in his father. The patient's vital signs on presentation are: blood pressure 120/80 mm Hg, pulse rate 80 beats/minute, and respiratory rate 16 breaths/minute. The physical examination reveals a patient with multiple bruises and a history of frequent nosebleeds. Further evaluation reveals low levels of von Willebrand factor (VWF) in the patient's blood. The patient is diagnosed with von Willebrand disease. The patient is started on desmopressin therapy to increase the levels of VWF in his blood and to prevent bleeding episodes. What is the signaling pathway of desmopressin?